Building and Controlling Dwarf Railroad Signals on a Budget

A NOTE ON SWITCH MACHINE AUXILIARY CONTACTS: Most – but not all – switch machine motors include one or two sets of auxiliary contacts that allow you to determine whether the turnout is in the straight or diverging position. Auxiliary contacts are included with Tortoise, Blue Point, Walthers Layout Control System, and Rapido RailCrew machines. Atlas switch machines do not provide auxiliary contacts; and as far as I can determine, neither do the Kato Unitrack switch machines.

A NOTE ON SOURCE VOLTAGE: The circuit and the PCBs will work with any input DC voltage above 3 volts, but you’ll need to adjust the resistances. Be careful: Above about 24 volts, you may need to use ½ watt resistors. The PCB board is designed for ¼ watt resistors, so the larger resistors may not fit.

A NOTE ON DRIVING TWO OR MORE LEDS IN PARALLEL: If you want to apply power to more than one LED in parallel at a time, you’ll need to reduce the resistance – otherwise, one LED will “steal” all the power. In the bicolor device shown here, I used 1000 Ohms on both the red and green LEDs.

ORDERING YOUR OWN CUSTOM PCB: Download the zipped Gerber files (see below) or create your own. Visit jlcpcb.com and click Order Now. You will be prompted to upload your zipped Gerber files. Expect to pay about $2 for five identical boards (plus shipping).

Links to items mentioned in this video. (Note: I am NOT endorsing any particular product(s), nor am I compensated by or connected to any of the companies mentioned.) I do NOT guarantee that these links will give you the best available price! Consider these links to be a starting point for your search.

HO scale Dwarf Signal Kit: https://www.eve-modeler.com/products/jtd19-10-sets-railway-dwarf-signal-ho-oo-scale-led This is the ground mount style. There is also a short mast mount style: https://www.eve-modeler.com/products/jtd21-10-sets-ho-oo-scale-target-faces-railway-dwarf-signal-2-aspects-led

3 mm bicolor LEDs: https://www.amazon.com/gp/product/B077XDRNVR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Signal wire: I use this very thin wire from Tomar Industries. It’s incredibly expensive – almost 50 cents per foot – but it is easily concealed inside the model. https://tomarindustries.com/products/wire-ho-6080

Prototype Circuit Boards: https://www.amazon.com/gp/product/B0166GCD42/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Screw Terminal Connectors: https://www.amazon.com/dp/B07WKL6MRM?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 You’ll need both 2 pin and 3 pin connectors for this project. If your budget is limited, buy the three pin connectors and cut off the third pin to make your own 2 pin connector.

DPDT Switch: https://www.amazon.com/dp/B07F7PNDGM?ref=ppx_yo2ov_dt_b_fed_asin_title

Resistor Assortment: https://www.amazon.com/BOJACK-Values-Resistor-Resistors-Assortment/dp/B08FD1XVL6/ref=sr_1_3?crid=1AUR2ADQ2G5K4&dib=eyJ2IjoiMSJ9.BNJiYWYIJ8SO47xLLe9PpvWloRhMG56MSyDMENYT-Wxq_gSwosa-76yVI-B4Vgr0GspU6pNSV44JHkF3z9wmvEUdY6ywVfk2H2J7bfuwDRtQqvEb1_nzJ_UKk8FwzVI_h-rh36g0xWQI3rhtL3muWJp88XEajWCPVXWR-pPdJR9JOdKLgVGbAoWauGC2ZoTYXvITAnC41_CMgaewrDLdng1_UQ0_34DPu5GIl-FiEjk.8Xdbi4TeYim9YWuQdsjOzchwFiBPOQnYsQQFxqkUyzg&dib_tag=se&keywords=resistor%2Bassortment&qid=1727752323&sprefix=resistor%2Bassortment%2Caps%2C173&sr=8-3&th=1

Hookup wire: I buy all of my hookup wire from Remington Industries: https://www.remingtonindustries.com/hook-up-wire/?gad_source=1&gclid=CjwKCAjw9eO3BhBNEiwAoc0-jdbfHxi4vQhtab_8u4yUuvkNuVcfp7fZrI4emVOjI_PgB8YJQAAa8RoC9hwQAvD_BwE They provide both stranded and solid wire in a wide variety of gauges and insulation colors, and you can buy as little as 25’ or as much as 5000’ (!) on a spool.

You can download the Fritzing software here: https://fritzing.org/download/ You’ll need to make a 10 Euro donation to download the most recent version (that’s about $9.30 as of October 2024.)

Signal Controller Design Files: https://github.com/RJW496/DRGW-HO This link is to my GitHub page. You need either “Dwarf Signal Controller v1.1_.zip” or “Dual Dwarf Signal Controller v1.1_.zip”. When you click on the zip file name, you’ll open what appears to be an empty file. Click the “View raw” link – this will allow you to download the zipped file.

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This video was edited using Shotcut for Linux. Video footage and still images were recorded using a Galaxy A10e phone and a Nikon D7100 camera.
The photo of two dwarf signals on either side of a single turnout is a screenshot taken from this video by Bill Masters describing quite a different method of wiring dwarf signals: https://www.youtube.com/watch?v=tPTi-EBVFgY